1. Field of the Invention
The present invention relates to an aircraft actuator including a hydraulically driven cylinder that is attached to a control surface or a horn arm member, and a reaction link that is provided pivotally with respect to the cylinder and the control surface.
2. Description of Related Art
An aircraft is provided with control surfaces that are formed as moving surfaces (flight control surfaces) and are configured as an aileron, a rudder, an elevator, and the like. As aircraft actuators for driving such control surfaces, aircraft actuators as disclosed in JP H5-097095A and JP S62-165007A are known that include a hydraulically driven cylinder that is attached to a control surface or a horn arm member attached to the control surface, and a reaction link that is provided pivotally with respect to the cylinder and the control surface.
As described above, the aircraft actuators disclosed in JP H5-097095A and JP S62-165007A include a reaction link. From the viewpoint of achieving weight reduction while securing a specific strength, such a reaction link is made of light metal such as titanium alloy or aluminum alloy. Also, the reaction link that is provided pivotally with respect to the cylinder and the control surface is formed in the shape of a portal including a pair of linear portions, a coupling portion, and a pair of bent portions, in order to stably drive the control surface via actuation of the cylinder. The pair of linear portions are disposed alongside each other and each extend linearly, and the coupling portion is provided so as to couple one end of each of the pair of linear portions on the same side to each other. The pair of bent portions are formed as connection portions between the coupling portion and the pair of linear portions. Also, the other end of each of the pair of linear portions is provided pivotally with respect to the other end of the cylinder, and the center portion of the coupling portion is provided pivotally with respect to the control surface. Note that each of the pair of linear portions is usually formed as a member that has a flange portion formed at each end in the width direction and thus has a cross section of an I-shape or H-shape, from the viewpoint of weight reduction.
However, even for a metal reaction link made of titanium alloy or the like in order to achieve weight reduction while securing a specific strength, there is a limit to weight reduction, and it is difficult to achieve a further weight reduction in the current situation. Furthermore, due to the influence of lift exerted on the control surface, a large tensile load and a large compressive load are exerted on the reaction link that is provided pivotally with respect to the cylinder and the control surface for driving the control surface. Since the reaction link is provided with a pair of large bent portions that are bent at substantially a right angle relative to a pair of linear portions, as described above, it is important to suppress buckling deformation due to a compressive load and secure the buckling strength required for that purpose, in addition to suppressing the above-described deformation due to a tensile load and securing the tensile strength required for that purpose, in order to achieve a further weight reduction.